Hemlock Woolly Adelgid (Adelges Tsugae) Surveillance

1 St. Lawrence Eastern Lake Ontario Partnership for Regional Invasive Species Management Special Note This report is to be considered as an addendum to the field reports from 2015 and 2016. The previous reports are attached to the end of this report. 2017 Field Survey Addendum to Hemlock Woolly Adelgid (Adelges tsugae) Surveillance Figure 1: Stand of Eastern Hemlocks at Salmon River Falls. Photo taken by Alicia Wood. SLELO-PRISM Early Detection Surveillance August 31th, September 5-7th & 11-12th, 2017 Report prepared by Bryna Daykin and Alicia Wood, 9/15/2017 Introduction and Background1 Hemlock woolly adelgid (Adelges tsugae), native to Asia, is a small aphid-like insect that threatens the health and sustainability of eastern hemlocks (Tsuga canadensis). Hemlock woolly adelgid (HWA) was first discovered in the United States in 1951 near Richmond Virginia, and has since spread throughout the northeastern U.S. and into the Midwest. Decline and mortality of hemlock after an infestation typically occurs between 4 and 10 years. Hemlocks stressed by drought, poor site conditions, disease, and other insect pests will show accelerated rates of mortality. 2,3 1 Introduction and Background edited from the 2015 SLELO-PRISM Hemlock Wooly Adelgid Survey, by Ben Hansknecht and Caitlin Muller: http://www.sleloinvasives.org/wp-content/uploads/2017/06/HWA-2015-Report-PDF.pdf 2 Information obtained from the United States Department of Agriculture Forest Service: https://www.na.fs.fed.us/spfo/pubs/pest_al/hemlock/hwa05.htm 3 Information obtained from the St. Lawrence Eastern Lake Ontario Partnership for Regional Invasive Species Management SLELO-PRISM: http://www.sleloinvasives.org/about-invasives/prevention-watch-list-species-in-slelo-region/hemlock-woolly- adelgid/ SLELO-PRISM c/o The Nature Conservancy 269 Ouderkirk Road. Pulaski, NY 13142 Rob Williams, Coordinator 2 Figure 2: From left to right: HWA eggs, HMA crawler, HWA nymphs in dormancy on the bases of the needles on an Eastern Hemlock tree, adult HWA. Photos from left to right taken by: Shimat Joseph, University of Georgia, Bugwood.org; Kelly Oten, North Carolina Forest Service, Bugwood.org; Ashley Lamb, Virginia Polytechnic Institute and State University, Bugwood.org; Michael Montgomery, USDA Forest Service, Bugwood.org. HWA is active in cooler months and dormant during the summer, producing two generations per year. HWA can only reproduce sexually on specific species of spruce trees which are not present in North America. Due to this, reproduction only occurs here asexually by parthenogenesis. This means that all HWA in North America are females, and that it only takes one HWA to create an infestation on a tree. There are six developmental stages for HWA: the egg, four nymphal instars (crawler) stages, and the adult (Figure 2; Figure 3). The crawlers are a dark reddish-brown to Figure 3: Hemlock Woolly Adelgid annual life purple-black in color and are typically found along the cycle. Photo obtained from the United States branches of hemlocks. These crawlers will attach to the Department of Agriculture, bases of Eastern hemlock needles by mid-July and https://www.nrs.fs.fed.us/disturbance/invasive_s pecies/hwa/additional_resources/. become dormant. These immatures remain dormant until mid-October, at which point they resume feeding. As they feed they produce waxy “wool” like filaments that are secreted out of their pores, which serve as a protective cover to prevent the insect from drying out. Adults produce reddish eggs within these masses from March-June (Figure 2; Figure 3). The sticky, woolly covering allows the eggs to spread by attaching to deer, birds, other forest dwelling mammals, and by the wind. The woolly masses are present from October-June, and are the easiest way to detect a HWA infestation (Figure 4). 2,3,4,5,6 4 Information obtained from the University of Massachusetts at Amherst Extension Services: https://ag.umass.edu/landscape/fact- sheets/hemlock-woolly-adelgid-frequently-asked-questions 5 Information obtained from Maine’s Department of Agriculture, Conservation and Forestry: http://www.maine.gov/dacf/mfs/forest_health/insects/hemlock_woolly_adelgid_fact_sheet.htm 6 Information obtained from the Encyclopedia of Life: http://eol.org/pages/7669301/details SLELO-PRISM c/o The Nature Conservancy 269 Ouderkirk Road. Pulaski, NY 13142 Rob Williams, Coordinator 3 Figure 4: Hemlock Woolly Adelgid masses on Eastern Hemlock tree branches. Left photo taken by Steven Katovich, USDA Forest Service, Bugwood.org. Right photo taken by Pennsylvania Department of Conservation and Natural Resources - Forestry, Bugwood.org. Look-alikes of HWA woolly masses include spittlebug (Aphrophora saratogensis) foam, oak skeletonizer (Bucculatrix ainsliella), elongate hemlock scale (Fiorinia externa), drops of pine sap, bird feces, and spider egg sacs (Figure 5). To distinguish these, note that the HWA woolly masses resemble cotton balls, are immobile, are not silky or stretchy but rather waxy, and don’t appear painted on as pine sap and bird feces do. Additionally, placement of the HWA woolly masses can help distinguish the species, as HWA masses are always found on the branches at needle bases, while spider eggs are often laid on the needles. Additionally, spider eggs will never appear as clumped as HWA masses (Figure 4; Figure 5). 8 Figure 5: HWA look-alikes. From top left to top right: elongate hemlock scale7, oak skeletonizer8, spittlebug foam7. The bottom left photo is pine sap8 and both the bottom middle and bottom right photos are spider eggs9. Note the placement of the spider eggs on the needles, a characteristic that distinguishes them from HWA woolly masses. 7 Photos obtained from Ohio Department of Natural Resources: http://ohiodnr.gov/hemlock-woolly-adelgid-in-ohio/learn-more- about-hwa/post/hwa-or-not-look-alike-pests 8 Photos obtained from University of New Hampshire Extension Services: https://extension.unh.edu/resources/files/Resource002109_Rep3114.pdf 9 Photos taken by Alicia Wood and Bryna Daykin SLELO-PRISM c/o The Nature Conservancy 269 Ouderkirk Road. Pulaski, NY 13142 Rob Williams, Coordinator 4 This insect feeds directly from the storage cells of hemlocks, causing needle death and progressing to twig and branch death. The needles lose color becoming yellow and grey, dry out, and fall off branches. As the insects’ feeding progresses the terminal buds die, preventing new shoot growth. Within two years this dieback can be observed in major limbs. The decline in health typically occurs first from the bottom limbs before continuing upward toward the top of the tree. HWA infestations cause death to mature hemlock trees within 3 to 10 3,4,5,6,10 years. Figure 6: Map of Hemlock Woolly Adelgid detections in New York State. Map created by the NYS Department of Environmental Conservation, http://www.dec.ny.gov/animals/86382.html. The blue line on the map outlines the Adirondack region. HWA has been observed in Cayuga and Onondaga Counties, which borders the SLELO- PRISM (Figure 6). This species is considered a ‘Prevention “Watch-list” Species’, whose arrival could be detrimental to the ecosystems found within the PRISM. One area of special concern is the southern Tug Hill region. Eastern Hemlock is ecologically important, as it is frequently found along exposed slopes, protected gorges, and streams. Hemlock creates a cool, damp, and shaded environment which supports a wide variety of organisms, including salamanders. Throughout the winter hemlock provides shelter and food for wildlife. Studies of forests damaged by HWA in the southern U.S. have shown that a decline in hemlock populations can cause a decline in other plant and animal populations, producing drastic changes to ecosystem processes. 3,10 10 Information obtained from Cornell University Cooperative Extension: http://www.nyis.info/index.php?action=invasive_detail&id=24 SLELO-PRISM c/o The Nature Conservancy 269 Ouderkirk Road. Pulaski, NY 13142 Rob Williams, Coordinator 5 Survey Methods and Objectives The priority conservation area for this survey was the southern Tug Hill region, on the southern-most side of the SLELO-PRISM. This section of the SLELO-PRISM is considered more likely to contain HWA as this species has been found in other southern regions of the state (Figure 6). The eleven sites surveyed in 2015 and 2016 were resurveyed in 2017. These sites were selected based on their high abundance of eastern hemlock stands, and included Salmon River Falls, Chateaugay State Forest, Selkirk Shores State Park, Mexico Point State Park, Happy Valley Wildlife Management Area, Mad River State Forest, Forest Park, Buck Hill State Forest, Clark Hill State Forest, Penn Mountain State Forest, and Trenton Greenbelt (Figure 7; Figures 9-19). These sites were surveyed for points with dense stands of eastern hemlock trees, consisting of at least 20 trees. Additionally, the Early Detection Team assessed the overall health of the eastern hemlock trees at each point. Signs of poor health including dieback, loss of needles, and needle discoloration (Figure 8) can indicate tree infestation by the HWA species. However, these symptoms can also be a result of other issues, such as nutrient deficiency. Figure 7: Areas surveyed for Hemlock Woolly Adelgid within the SLELO-PRISM. To locate and mark new points at each of the survey sites, a handheld Garmin GPSmap 60CSx was used. Unlike previous years, the 2017 survey did not involve an extensive examination of the trees at each stand, as the survey was conducted in late summer when the cotton-like masses were not yet present on branches. However, samples were taken from trees at each point and were closely examined under microscopes by the Early Detection Team for nymphs. At this time of year, HWA nymphs are found in dormancy on the bases of eastern hemlock needles (Figure 2; Figure 3). No HWA nymphs were found on any of the branches examined. The purpose of this survey was to determine priority areas for volunteers to come back to and survey in mid-October, when the woolly masses are visible, as shown in Figure 4.

Load more